Health behavior may be influenced by age, beliefs, and symptomatology. To examine age-related health beliefs and behaviors with respect to six diseases (the common cold, colon-rectal cancer, lung cancer, heart attack, high blood pressure, and senility), 396 adults (196 males, 200 females) divided into three age groups completed a questionnaire assessing health practices, perceived effectiveness of preventive behaviors, illness attributes, coping, and symptoms as disease warnings. Age group composition was as follows: (1) 173 adults, aged 20-39; (2) 111 adults, aged 40-59, and (3) 112 adults, aged 60 or older, and responses were analysed according to group. Results showed that all subjects reported engaging in health promotion behaviors (e.g., eating a balanced diet, getting enough sleep) at least occasionally. All behaviors showed increased frequency of performance with age except aerobic exercise and physical exertion which decreased with age. Although most actions were not perceived as effective, some actions were accepted as effective for specific diseases (e.g., restricting salt to prevent high blood pressure). Older adults were more likely to believe that illness could be prevented by avoiding strenuous exercise and avoiding harmful health behaviors, while younger adults believed that strenuous exercise prevented disease. Finally, older persons saw themselves as more vulnerable to the six illnesses, and they believed the illnesses would be more severe if they contracted them. (Numerous tables are appended to highlight the results). (BL)